Core-drying means



J. c. DAVIS. CORE DRYING MEANS.

APPLICATION FILED JUNE 7' 1919.

1,335,222. v Patentd Mar.30,1920.

UNITED STATES PATENT OFFICE.

JAMES C. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR T0 AMERICAN STEEL FOUNDRIES,

OF CHICAGO, ILLINOIS, A CORPORATION OF NEW JERSEY.

CORE-DRYING MEANS.

Specification of Letters Patent." Patented B131. 30, 1920.

Application filed June 7, 1919. Serial No. 302,402.

-with a stack conveniently located to carry off the hot gases by natural draft through. variously arranged openings.

The combustion temperature of the gases used for drying cores as they come from either a coal-fired'or oil-fired furnace is approximately 1600 degrees. The correct temperature for drying cores is approximately four hundred to four hundred and twenty degrees. Certain compounds are used for making up the mixture for dry sand cores which results in a strong and durable core if the core is baked or dried at the correct temperature. These compounds are such, however, that they disintegrate or become burned or melted if they are baked at too higha temperature. A mixture or compound for cores might be made which would stand a higher baking temperature but such cores would be too hard and would offer too much resistance to crushing or the natural shrinkage of castings. The best dry sand core is one that is just hard enough to be handled without breaking and of suflicient strength and no more to hold its shape in the mold while thelatter is being filled with molten metal and as soon as the mold is filled and the metal begins toshrink, the core should give way to this shrinkage. Broadly speaking therefore there is a definite ratio existing between the general hard ness of the core and the temperature at which it should be baked. It is found by experience that a core of a given composition baked at a temperature of approximately four hundred to four hundred and twenty degrees is the most satisfactory. This composition will not stand a baking, temperature much beyond four hundred and twenty degrees without injury.

Accordingly one object of my invention is to reduce the temperature of gases from furnaces from approximately 1600 degrees to the correct core baking temperature of approximately four hundred and twenty degrees, and at the same time do this efiiciently by conserving heat units usually allowed to pass out of the oven as waste gases.

Another object of my invention is to provide a simple and efficient heat saving means for reducing the temperature of core baking gases adapted to meet the requirements for successful use.

These and other objects are accomplished by means of the arrangement disclosed in the accompanying drawing, the single figure of which is a sectional view of a core-drying oven embodying myinvention.

This core-drying oven 10 has a hot gas funnel-shaped inlet 11 in the floor 12 thereof and has a plurality of exhaust openings 13 in the roof 1 1 thereof, said exhaust openings leading to a chamber 15.11aving an outlet stack 16 controlled by a damper 17 and a second outlet portion 18, which communicates by a pipe 19 with a centrifugal fan 20. The core-drying oven also has an exhaust opening at one end 21 near the floor 12, gases being exhausted through a pipe 22 to the same centrifugal fan 20. Blast gates 23 and 24'may be provided for controlling the suction created by the fan 20 through the pipes connected with the core-drying oven. By having an exhaust opening near the bottom of one end of the oven, the gas inlet 11 being directed toward the opposite end 25 of the own, not only do the hot gases pass upwardly through the oven 10 and out through the exhaust openings 13, but they also circulate in the oven and out through the exhaust passageway 22 to the fan 20, thereby maintaining the temperature in all parts of the core-drying oven 10 substantially uniform.

Instead of providing a coal-fired furnace for supplying hot products of combustion to the oven 10, I provide an oil-burner 26, the oil being supplied through a pipe 27 and mixed with a combustion supporting medium in a chamber 28 and tube 30, the combustion supporting medium being controlled in any suitable manner by valves or shutters 29. The hot flame produced by the burning of oil projects or extends through the tube 30 which directly communicates with the oven inlet 11. Surrounding the tube 30 is an annular passageway 31 through which a diluent passes. It isvapparent that if the diluent were cold air the thermal efiiciency of the core-dryin equipment would be seriously impaired. 0 overcome this waste of heat and to make the operation of the oven eflicient, I use as a diluent the exhaust gases from the oven which are supplied by the fan 20 through a pipe 32 to the annular chamber 31 surrounding the tube 30 through which the oil flame is projected. The temperature of the exhaust products of combustion passing through the pipe 32 and into the annular chamber 31' is relatively high as compared with cold air, accordingly less oil may be burned for producing the desired temperature within the oven 10, or, in other words, a greater quantity of hot product of combustion at four hundred and twenty degrees may be supplied to the oven 10 with a given amount of oil where exhaust gases are used as a diluent rather than cold air. The exhaust gases supplied through the annular chamber 31 surrounding the tube 30 have an iniector action upon the hot products of combustion drawn through the tube 30. The tube 30 is supported centrally within the annular passageway 31 by apertured collars 33 whereby the passage of the gases through the annular passageway 31 is not seriously impeded.

By means of this arrangement eflicient results are obtained in the baking of cores in a manner to meet all of the requirements'in core baking. a i

It is my intention to cover all modifications of the invention falling within the spirit or scope of the following claims.

I claim 1. In core-drying means, the combination,

after treating cores therein, and means reg- 1ster1ng wlth said inlet throughwhich hot products of combustion may pass, there be- 3. In core-drying means, thecombination of an oven having an inlet and an outlet whereby hot products of combustion may pass into said oven and pass out of same after treating cores therein, means registering with said inlet through which hot products of combustion may pass, and means arranged adjacent said other means through Which the exhaust gases from said oven may pass to mix with the hot products of combustion to decrease the temperature of the latter preparatory to passing into said oven.

4:. In core-drying means, the combination of an oven having exhaust openings in the top and one end thereof, and means for directing hot products of combustion into said oven toward the opposite end thereof whereby the hot products of combustion are caused to circulate throughout the oven before passing therefrom.

5. In core-drying means, the combination of an oven having exhaust openings in the top and one end thereof, and means entering the'fioor of the oven for directing hot products of combustion into said oven toward the opposite end thereof whereby the hot products of combustion are caused to circulate throughout the oven before passing therefrom. I

6. In core-drying means, the combination of an oven having exhaust openings in different walls thereof, and means for directing hot products of combustion into said oven toward another wall thereof whereby the hot products of combustion are caused to circulate throughout, the oven before pass ing therefrom.

Si ed at Chicago, Illinois, this 29th day of ay, 1919.

JAMES C. DAVIS. 

